Advisory Details

January 13th, 2022

Microsoft Windows SilentCleanup Link Following Local Privilege Escalation Vulnerability

ZDI-22-049
ZDI-CAN-14660

CVE ID CVE-2022-21838
CVSS SCORE 7.0, AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
AFFECTED VENDORS Microsoft
AFFECTED PRODUCTS Windows
VULNERABILITY DETAILS

This vulnerability allows local attackers to escalate privileges on affected installations of Microsoft Windows. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.

The specific flaw exists within the SilentCleanup scheduled task. By creating a symbolic link, an attacker can abuse the task to delete a folder. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of SYSTEM.

ADDITIONAL DETAILS Microsoft has issued an update to correct this vulnerability. More details can be found at:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2022-21838
DISCLOSURE TIMELINE
  • 2021-09-03 - Vulnerability reported to vendor
  • 2022-01-13 - Coordinated public release of advisory
CREDIT Abdelhamid Naceri
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